Physicians make use of catheters today in medical procedures to gain access into interior regions of the body for diagnostic and therapeutic purposes. It is important for the physician to be able to precisely position the catheter within the body to gain contact with a desired tissue location.
The need for precise control over the catheter is especially critical during procedures that ablate myocardial tissue from within the heart. These procedures, called ablation therapy, are used to treat cardiac rhythm disturbances.
During these procedures, a physician steers catheter through a main vein or artery into the interior region of the heart that is to be treated. The physician then further manipulates a steering mechanism to place the electrode carried on the distal tip of the catheter into direct contact with the endocardial tissue. The physician directs energy from the electrode through myocardial tissue either to an indifferent electrode (in a uni-polar electrode arrangement) or to an adjacent electrode (in a bi-polar electrode arrangement) to ablate the tissue.
Before ablating heart tissue, physicians often examine the propagation of electrical impulses in heart tissue to locate aberrant conductive pathways and to identify the arrhythmia foci, which are ablated. The techniques used to analyze these pathways and locate foci are commonly called "mapping."
Conventional cardiac tissue mapping techniques use multiple electrodes positioned in contact with heart tissue to obtain multiple electrograms. These conventional mapping techniques require invasive open heart surgical techniques to position the electrodes on the interior or exterior surfaces of the heart.
An alternative technique of introducing multiple-electrode arrays into the heart through venous or arterial accesses to map myocardial tissue is known. Compared to conventional, open heart mapping techniques, endocardial mapping techniques, being comparatively non-invasive, hold great promise. Multiple electrogram signals obtained from within the heart can be externally processed to detect local electrical events and identify likely foci.
Once mapping identifies the foci, an ablation electrode is steered into position in contact with a focus site. At least, in theory, this is the goal sought to be achieved. In actuality, though, the task of remotely guiding an ablation element within the blood pool of a beating heart to a particular focus site can be, at best, problematic.
There is the need to provide simple, yet reliable, ways of guiding electrode elements within the heart, or within other interior parts of the body, to precise locations targeted for diagnosis or treatments.